1. Field of the Invention
The base of the security/prevention system is an electronic device which has the capability of joining the performance of two functions, i.e. prevention of road accidents and theft protection of vehicles, using the principle of joint use of frequencies, whereby interference with the device's operation is prevented.
The invention allows, on the one hand, such application in road traffic safety, in which an electronic security device installed in a vehicle provides passive and active warning of participants in the traffic as to momentary dangers requiring quick reaction of the driver.
On the other hand, the device allows such application in road traffic safety, in which an electronic security device protects the vehicles against theft; the device comprises three base units, i.e. an electronic security device, which is installed in the vehicle and intended for transmitting messages about theft, a pocket receiver, and a network of receiver devices distributed at all locations of importance to the reception of the transmitted messages. The invention belongs to classes G01S 5/00, 5/02, 5/14, 3/50, G08G 1/01, 1/09, 1/16, 1/127, G08B 25/01, 25/10 of the International Patent Classification.
2. Description of the Related Art
From the PCT document 91/04081, a system is known for the exchange of information--over RF signals--between stationary stations and moving vehicles. It offers the possibility of changing the data stored in the memory of a device installed in vehicles, while they are moving. The stationary devices trigger the devices installed in the vehicles which are passing by, and get the required data from them. A drawback of this system is the small range of the device.
The PCT document 92/06698 describes bidirectional exchange of data over radio (using one half-duplex frequency) between vehicles and fixed stations which make up a network and which are linked with a center. Interference suppression on the channel is carried out by means of a time-division multiplex and by spread centrum technology. The accent is on the methods of locating the position of a vehicle with respect to the receivers in the network.
In the EP document No. 290 635, a device is described which would prevent collisions of vehicles, especially at crossroads, and also elsewhere on the road. It would provide identification of crashes, even outside the field of vision, by equipping each vehicle with one transmitter and two receivers. The signals would be optical, and the system would provide an additional system for road marking with special signs.
In the EP patent document No. 441 576, a device is described which comprises a transmitter and a receiver part linked into a system with sensors of collision and acceleration. The frequency of the transmitter and the receiver is not specified, and an aerial is provided which is oriented only in the driving direction. The system would be able to make out whether the vehicle approaches or moves away from the transmitter, on the basis of Doppler effect, or on the change of power of the received signal.
The EP document No. 514 996 describes a system of theft protection of vehicles. In the case of theft, the system would emit a code identifying the vehicle. Roadside receiver & coordination stations would receive the code and send it to a centre where the position of the vehicle could be calculated. The system operates at a frequency of 10-15 MHz and 10-15.6 GHz (communication with a satellite). The calculation of the position is made possible by means of the time delay between the signals received at different receiver stations. It also uses a gyroscope.
In the EP document No. 446 985, a system of information within existing RDS system is described, where data are transmitted beside the signal of a commercial radio station. The system provides the breaking down of information by areas. It is evident from the code of a message which area is involved. The receiver is capable of identifying the code and it only receives the desired data. Data are grouped, and each group has its own delay frequency, while the user can select the reception.
In the PCT document No. 90/05349 a system for transmitter position identification is described. The system comprises two parts, i.e. a part which is installed in vehicles and comprises three transmitters and a receiver, and a part which is installed in fixed control centres and has three receivers and a transmitter. The system is based on the principle that each of the three transmitters has its own frequency and a different power. This makes the first transmitter audible within a radius of 50 km, the second within a radius of 25 km, and the third within a radius of 1 km. A control system on a fixed frequency requests the transmission and gives the desired frequency. Depending on the frequency that "hears" it, it defines the distance and transmits the desired data to it.
So far, drivers have only had the possibility of audible (horn or siren) or visual signalling (lights, blinkers or blinking signal lights). Also, in prior art solutions, the given technical problem has not been solved completely and in a complex way, but only partially. There exists, for example, a possibility of calling the driver's attention upon the dangers in traffic over a radio receiver, however, only for certain types of traffic information (road-blocks, hold-ups or traffic jams, queues, slippery road, fog . . . ). For momentary dangers, every driver may find himself in, however, this way of alerting is not sufficient. A similar situation is that with vehicles on urgent ride, which only alert by blowing the horn, and are often not heard by the participants in traffic, or they are heard only at a place where it is impossible to give way.